1. Field of the Invention
This invention pertains to a method and apparatus for treating obesity. More particularly, this invention pertains to an apparatus and method for treating obesity with an implant in the gastrointestinal system to alter at least one of satiety, absorption and digestion.
2. Description of Prior Art
A. Obesity as a World-Wide Health Dilemma
Morbid obesity and its concurrent health risks (including diabetes, heart disease and other ailments) are of near-epidemic proportions in industrialized societies. A wide variety of treatments have been proposed and attempted to treat morbid obesity with a wide variety of efficacy and associated morbidity. These treatments include techniques to reduce stomach volume, alter gastric and intestinal motility, and alter the absorption of nutrients in the small intestine.
Clearly, obesity is a complex disease having physiologic, social and psychological components which are not fully understood. The complex nature and the enormous societal implication of obesity require a wide variety of treatment options be available to permit a physician to select a most appropriate option for a particular patient.
Even if all treatments were proven effective, no one treatment can meet the clinical needs presented by a diverse population. For example, current bariatric surgeries, such as the Roux-en-Y procedure as will be described, is not considered suitable for only so-called mildly obese patients (e.g., those with a Body Mass Index less than 35). Also, for extremely obese patients, operative risks may make this procedure undesirable.
Less invasive procedures (such as gastric banding, as will be described) have reduced surgical risk. Unfortunately, they suffer from reduced efficacy (and they are not without risks). Further, efficacy may be culturally biased. Namely, gastric banding studies show reduced efficacy in North American patients compared to European patients.
B. Selected Obesity Treatments
a. Surgical Options (Non-Device)
i. Gastric Volume Reduction
Surgical approaches to gastric volume reduction include minimally invasive surgery, open surgery and endoscopic approaches to gastric volume reduction. Many such procedures have been tried and some have been abandoned due to lack of efficacy or unacceptable morbidity and mortality.
The gastric volume reduction procedures include vertical and horizontal gastroplasty in which sutures, staples or other fixation devices are used to join opposing surfaces of the stomach to create a reduced volume pouch and thereby reduce caloric intake.
Gastric stapling, as used herein, refers to staples or stitches in the stomach to reduce stomach size. These include horizontal gastroplasty and vertical gastroplasty.
Surgical gastric volume reduction is focused on reducing the fundus to induce satiety. Recent studies suggest antral volume more directly influences satiety. Strum, et al., “Energy Intake and Appetite are Related to Antral Area in Healthy Young and Older Subjects”, American Journal of Clinical Nutrition, 80(3), pp. 656-657 (2004).
Less invasive techniques for restricting the volume of the stomach also include a gastric partition in which the stomach wall is endoscopically cinched together to form a reduced size pouch. The cinching is performed using commercially available products such as the Bard EndoCinch™ and the Wilson-Cook Sew-Right™ cinching equipment. Such surgical equipment is generally described in U.S. Pat. No. 5,088,979 to Filipi et al. issued Feb. 18, 1992; U.S. Pat. No. 6,302,917 to Dua et al. issued Oct. 16, 2001 or PCT International Publication No. WO 01/89393 published Nov. 29, 2001.
It has been recognized that gastric volume reduction does not address all mechanisms associated with obesity. For example, patients with gastric volume reduction can defeat the effectiveness of the gastric volume reduction by modifying eating habits. For instance, a patient may graze continuously on small volume, high caloric food or may replace solid foods with high caloric liquid foods.
ii. Surgeries with Malabsorptive Components
To address deficiencies associated with gastric volume reduction, treatments have been suggested and developed for reducing the amount of nutrient absorption in the small intestine (particularly in the upper and middle portions of the small intestine—the duodenum and jejunum, respectively).
In the duodenum, ducts from the pancreas and gall bladder discharge into the small intestine through small protrusions referred to as papilla. Commonly, pancreatic exocrine secretions (“PES”) flow from the pancreas in a pancreatic duct. Similarly, bile from the gall bladder flows through a bile duct. These ducts merge to form a common duct with discharges through a papilla into the duodenum. In some patients, the bile duct and pancreatic duct do not merge. They separately discharge into the duodenum at separate papilla which, usually, are in close proximity to one another.
Techniques to reduce nutrient absorption (commonly referred to as malabsorption treatments) include drug therapies for reducing lipids absorption. Such drug therapies have uncomfortable side effects, which can discourage a patient from complying with the drug therapy.
Other malabsorption treatments include surgical techniques for rerouting the intestinal system to bypass an extended portion of the small intestine. These include a so-called jejunoileal bypass. Not commonly used due to unacceptable mortality rates, a jejunoileal bypass would result in effective weight loss. Other techniques include the gastric bypass (or Roux-en Y) and duodenal switch. In both of these procedures, a large segment (e.g., in excess of 100 cm) of the small intestine (including the duodenum) are bypassed so that food content is rerouted from a small pouch formed in the upper portion of the stomach to the jejunum. As a result, the absorptive length of the small intestine is significantly shortened thereby reducing the amount of nutrients which are absorbed into the body and which support or lead to weight gain. These procedures combine the benefits of gastric volume reduction with malabsorption. Unfortunately, such surgical procedures are extremely invasive.
b. Implantable Mechanical Devices
i. Gastric Volume and Delayed Gastric Emptying
1. Gastric Banding
Less invasive techniques are suggested for placing a band (referred to as LAP bands) around an upper portion of the stomach to act as a belt to reduce the size of the stomach and create a small passageway (a stoma) from a small upper pouch to the remainder of the stomach. An example of a LAP band is shown in U.S. Pat. No. 5,266,429 to Kuzmak dated Jul. 13, 1993. LAP bands and other gastric bandings are disclosed in Schauer, et al, “Surgical Management of Gastroesophageal Reflux Disease in Obese Patients”, Seminars in Laparoscopic Surgery, Volume 8, Number 4, pages 256-264 (2001). Such LAP bands wrap around a portion of the fundus to create a greatly reduced volume portion of a fundus above the LAP band. Such bands create an upper chamber above the band to create a sensation of satiation after consuming only a small volume of food. See also, U.S. Pat. No. 5,549,621 to Bessler et al., dated Aug. 27, 1996; U.S. Pat. No. 5,226,429 to Kuzmak dated Jul. 13, 1993 and U.S. Pat. No. 4,592,339 to Kuzmak et al. dated Jun. 3, 1986.
2. Intra-Gastric Balloons
Other techniques for reducing gastric volume size include placement of obstructions within the stomach. These include intra-gastric balloons which are filled with saline to reduce the effective volume of the stomach. Examples of such balloons or other intragastric devices include those shown in U.S. patent application publication No. US 2001/0037127 to de Hoyos Garza published Nov. 1, 2001 (describing a percutaneous intragastric balloon to treat obesity); U.S. patent application publication No. 2002/0055757 to Torre, et al., published May 9, 2002; U.S. patent application publication No. 2004/0093091 to Gannoe, et al., published May 13, 2004 (describing an anchored intragastric balloon); U.S. patent application publication No. 2004/004357 to Gannoe, et al., published Mar. 4, 2004 (describing various techniques for retaining an intragastric balloon in a location in the stomach) and U.S. patent application publication No. 2003/0158601 Silverman published Aug. 21, 2003.
3. Pyloric Narrowing
U.S. patent application publication No. 2004/0019388 to Starkebaum published Jan. 29, 2004 describes treating obesity by injecting bulking agents into the pylorus. U.S. patent application publication No. 2004/0037865 to Miller published Feb. 26, 2004 describes various techniques to narrow the pylorus to slow gastric emptying to treat obesity. For example, the '865 application describes injecting bulking or stiffening agents into the pylorus. The application also describes ablation or scarring to narrow the pylorus as well as suturing the pylorus to narrow it.
U.S. patent application publication No. 2004/0089313 to Utley, et al., May 13, 2004 describes treating the pylorus to slow or meter gastric emptying. The '313 application describes treating tissue at the pylorus with an agent to tighten tissue or with a bulking agent. The application also describes treating the pylorus with an agent to interrupt afferent nerve impulses that trigger transient sphincter relaxation. The application also describes applying ablative energy to the pylorus, using magnets to tighten the pylorus or placing bands around the pylorus.
U.S. patent application publication No. US 2002/0188354 to Peghini published Dec. 12, 2002 teaches a device to treat obesity by obstructing the gastric outlet at the pylorus. The '354 application describes a device for obstructing the pylorus to create a sensation of satiety. The obstruction is a sandglass shaped device having bulges placed on opposite sides of the pylorus (one in the stomach, the other in the small bowel) with a narrow bridge spanning the pylorus. The device is formed of plastic and endoscopically delivered and fluid filled.
U.S. patent applications Publication Nos. US 2005/0033331 and US 2005/0055039 describe pylorus obstruction devices and methods.
4. Other
There fore-going description of prior art patents is not intended to be exhaustive. In the patent literature, there are many other suggestions for treating obesity. For example, U.S. patent application Publication No. 2003/0158601 to Silverman, et al., published Aug. 21, 2003 describes injections of implants in the stomach wall near the pylorus to inhibit gastric emptying. U.S. patent application Publication No. 2004/0172142 to Stack, et al., published Sep. 2, 2004 describes covered stent-like structures in the antrum and duodenum and bridging the pylorus.
ii. Devices to Promote Malabsorption
Less invasive techniques for restricting absorption have been suggested. They include bariatric sleeve devices such as those disclosed in US Patent Application Publication Nos. 2004/0092892 to Kagan, et al., published May 13, 2004 and 2004/0107004 to Levine, et al., published Jun. 3, 2004. In these techniques, sleeves are passed through the duodenum so that chyme (the contents of the intestines) are passed through the sleeve and do not interact with the absorptive walls of the intestine. The sleeves may be perforated to permit some of the chyme material to pass through the walls of the small intestine and be absorbed as nutrients. The sleeve of the '004 application includes a stent in the pylorus. The stent keeps the pylorus permanently open to induce a so-called “dumping syndrome”.
The bypass of the duodenum results in reduced absorption of desired nutrients (e.g., calcium) as well as undesirable nutrients (such as fat). Particularly, the loss of calcium absorption is significant since such loss can lead to osteoporosis.
A suggestion has been made to divert the digestive enzymes from the pancreas past the duodenum. Such a suggestion is shown in the afore-mentioned US Patent Application Publication No. 2004/0092892. In an embodiment of the '892 application, a tube is placed through the papilla and into the ducts of the gall bladder and the pancreas. A distal end of the tube is positioned significantly distal to the papilla such that pancreatic exocrine secretion and bile are diverted significantly distally to the papilla resulting in a reduction of absorption.
While pancreatic diversion is scientifically interesting, cannulation of the pancreatic duct carries significant risks. Such cannulation of the pancreatic duct has been performed in endoscopic retrograde cholangiopancreatography (ERCP). Patients under-going ERCP and/or related procedures are known to have a higher likelihood of developing pancreatitis. It has been reported that the incidence of post-ERCP pancreatitis can be as high as 28%. Fazel et al., “Prophylactic Pancreatic Duct Stenting: A Panacea”, Gastroenterology, Vol. 124, No. 4, pp. 1274-1275 (2003). Pancreatitis is a very serious disease which can be fatal.
c. Electrical Neural Stimulation
There have been a number of suggestions to treat obesity by applying electrical stimulation. For example, two patents assigned to Cyberonics, Inc. describe purported obesity treatments involving stimulation signals applied to the vagus nerve to up-regulate vagal activity to near a so-called “retching threshold”. These are U.S. Pat. Nos. 6,587,719 and 6,609,025).
U.S. Pat. No. 6,615,084 to Cigaina dated Sep. 2, 2003 (assigned to Transneuronix) delivers direct smooth muscle stimulation to the stomach through a laparoscopically placed lead connected to an implantable pulse generator. Similarly, U.S. Pat. No. 5,423,872 to Cigaina dated Jun. 13, 1995 describes placing electrodes on the abdominal wall.
A number of patents and patent applications are assigned to Intrapace Inc pertaining to an endoscopically delivered direct stimulation device for the treatment of obesity. Examples of these are U.S. Pat. No. 6,535,764; US 2003/0167025; US 2003/016024; WO 02/087657; and WO 02/089655.
Also, proposed stimulation therapies include technologies to provide direct gastric stimulation to create a ‘banding’ effect on the stomach formed by contracted muscle. U.S. Pat. No. 6,571,127 to Ben-Haim et al., dated May 27, 2003 describes applying a field to a GI tract to increase the force of contraction. U.S. Pat. No. 6,600,953 to Flesher et al., dated Jul. 29, 2003 describes a set of electrodes on the stomach which cause a contraction to decrease a cross-section of the stomach.
d. Electrical Neural Block
Recent novel treatments include vagal modulation to block neural impulses on the vagus nerve to down-regulate pancreatic exocrine secretion production as well as alter gastric accommodation. Such treatments are shown in U.S. Patent Application Publication No. 2004/0172086 A1 to Knudson, et al.